antique cycle 6v adding led headlamp

This magneto is nominally 6v. I've measure 4v to 16v through the rpm range. Max output is 35 to 40watts. It has a separate lighting coil but no rectifier or regulator. Headlamp and taillamp only. Not street legal. 6v lamps are dim to too often blown. 12v lamps are uselessly dim but last longer. Rather not add a battery unless it is a significant benefit. From the reading I've done so far LEDs are the only way to get significantly improved candlepower out of the headlight. This is what I'm contemplating. I hope someone can offer more expert advice on the direction I'm looking at. common as dirt full wave rectifier to give me dc at the start. http://www.amazon.com/Amico-Single-Bridge-Rectifier-KBPC5010/dp/B008DEU18G Adjustable Regulator so that I can recharge the batteries at the ideal level required of them. http://www./itm/LM338K-Linear-DC-or-AC-6V-30V-Out-DC-4-5V-28V-5A-Voltage-Converter-Adjustable-/221039147321?pt=LH_DefaultDomain_0&hash=item3376f5b939 Kit for 23USD that supplies a headlight and batteries. Rated 1200 top lumen, probably more like 800 in reality, but 15x what the 6v 21w incandescent that is in there presently is giving. http://www./itm/SecurityIng-1200Lm-CREE-U2-LED-Mini-Cycling-Bike-Light-Torch-Battery-Pack-US-/161074476663 No doubt there are major oversights to my plans. Since there is amazingly little info on the web for this type of application I'm starting at the bottom of the learning curve.

I did not want to add the year make or model since that information generally tends to distract from the topic when questions of completely non-oem retrofits are concerned. The info provided is perfectly adequate without such distractions such as "why on earth would you want to do that to xxxx bike?" "I wouldn't bother" etc. Yes, I've heard all of that before. And it's pure distraction. But for conformity's sake with the rules, it's a pair of 1981 single speed 50cc Puch mopeds (again,not to be licensed for the street).

IMO forget the linear voltage regulator, use a switching type buck-boost dc-dc converter. There are several in webland based on the LM2577 etc for a few dollars (3 Amps max). You may need a higher current version.

This is what I’m contemplating. I hope you might offer more expert advice on the direction I’m looking at. common as dirt full wave rectifier for dc output. http://www.amazon.com/Amico-Single-Bridge-Rectifier-KBPC5010/dp/B008DEU18G Adjustable Regulator, as you suggested, so that I can either run led directly or recharge the batteries at the ideal level required of them. http://www./itm/DC-DC-Step-Up-Down-Boost-buck-Voltage-Converter-… So I’m searching for a maximum brightness single LED SMD that I can experiment with within the existing reflector and pressed glass diffuser lens at different angles, depths, and possibly even mounted on the inside of the glass lens, heat xfer epoxy, facing rearward toward the reflector for optimum road lighting pattern. 3.X ~ 4.X volts. form factor size is not critical. Something like this unless a larger element is a better candidate. http://www.digikey.com/product-detail/en/XRCWHT-L1-R250-00901/XRCWHT-L1-R250-00901CT-ND/1923198 I’m a complete beginner except for a couple of days of web research. Would anyone offer some help as to how to set this up? Just connect the rectifier between the coil output and the regulator, adjust regulator for 4dc in, 4vdc out, and connect direct to LED SMD? Could it be that straightforward? Would it be better to incorporate three eneloop 1.2v rechargeables or even a 4v lead acid battery? Another off-the-shelf option is this headlamp recently purchased from Home Depot, package of two for 9.95. It incorporates a surprisingly bright, easily adequate for my needs, Cree XB-D element with three aux leds together running on three 1.5v alkaline aaa cells, 4.5vdc fitting the needs of this project quite well Pics of the innards... I hope I can get some advice here.   I'd really like to get this put together in some way that I can get max brightness out of this antiquated 4vac ~ 16vac magneto.

link to regulator should be http://www.aliexpress.com/item/DC-Boost-Buck-Converter-Input-4-35V-Output-1-25-25V-0-4A-Constant-Current-Voltage/556745984.html

And link to Home Depot headlamps http://www.homedepot.com/p/High-Power-LED-Headlamps-2-Pack-HD12OTB52/203409159#.UgxDlaw6Wmx

There are 2 distinct aspects to a project like this, namely: - powering of the LED(s) - charging of the batteries. As I recall, the original proposed light was a self contained LED with LiPo battery with a DC input (to charge the LiPos). In that case the dc-dc converter merely supplies the correct DC voltage and the light unit looks after the LED and battery charging. LiPos as with any Lithium battery requires a specific charging method else explosion or fire can result, hence you want to avoid that. Other battery types have their own charging methods. And the battery charging voltage will be different to what the LED(s) require, so 2 distinct voltage sources are required (unless you use whatever method the "light" uses to control that). Combined with the hassle needed to mount LEDs and lens them, buying a ready made unit seems a sensible way to go.

buying a ready made unit seems a sensible way to go. By that do you mean the Home Depot unit pictured above or any of the dozens and dozens of bicycle headlamps available on the web? That practically negates the whole exercise. I don't want to be constantly removing, recharging, batteries as the light output gets dimmer and dimmer. I want to use the lighting coil on the engine to keep the unit fully lit and stable enough to get max life out of the LEDs. I was recently recommeded a list of parts from DigiKey. I should be able to draw 3 to 3.5 amps from this coil. For this small a system a bridge rectifier such as this http://www.digikey.com/product-search/en?vendor=0&keywords=GBU10A-BPMS-ND should be an option with a suitable sized paralleled cap to smooth out ripple in the the dc output and negate the need to use a battery here since I have no need for accessories beyond head and taillights. And the rectifier ought to limit the top end to 12 ~ 13vdc. Dc/Dc conversion can be as compact and adequate as this... http://www.digikey.com/product-search/en?vendor=0&keywords=941-1042-ND It has an input range of 3.1VDC – 13.8VDC, and an adjustable output range of .6V - 5.1V. It can also output up to 30W (6A). This could be a viable option for powering white LEDs as most of them have a forward voltage in the 3.3-3.8VDC range. It may require more than one LED to reach desired light output. Since the DC/DC converter can only output up to 5.1V LEDs would have to be in a parallel arrangement so that their voltages were not additive. Probably the most difficult decision to make is identifying the ideal neutral white +/-4000K from among these pages http://www.digikey.com/product-search/en/optoelectronics/leds-high-brightness-power-modules/525140 Anyone else would like to weigh in here. I'd appreciate it. From there is the toughest choice. An ideal candidate, or pair of candidates (in

svejk wrote: I don't want to be constantly removing, recharging, batteries as the light output gets dimmer and dimmer.

You won't. The dc-dc converter plugs into the light's external DC power socket.

The progress of these LED SMD's is almost on a monthly acceleration curve. Diy'ing this with digikey or mouser smd's affords me the opportunity to experiment with precisely the pattern spread, Kelvin, manufacturer, mm width and length, etc, for 1/4 the cost of an off the shelf flashlight, the majority of parts of which I would be landfilling anyway. So just what is the 'latest and greatest' 3.x volt LED SMD available from these vendors today in near to a 4000k spread that is optimal for trail riding conditions (about 120 degrees)?